Conventionally, as a bearing for a high-speed rotating body, there is known a radial bearing that is used by being fitted on a rotating shaft. As such a radial bearing, there is a well-known radial foil bearing that is provided with a thin plate-shaped top foil that forms the bearing surface, a back foil that resiliently supports this top foil, and a cylindrical bearing housing that houses the top foil and the back foil. As the back foil of the radial foil bearing, a bump foil that consists of a thin plate molded in a corrugated shape is mainly used.
In the case of this kind of radial foil bearing, in order to prevent the top foil and the back foil from dropping out of the bearing housing, one end portion thereof (toe portion) is directly fixed to the bearing housing via spot welding or indirectly fixed via a spacer.
Also, as a structure that fixes in a mechanical manner instead of fixing by the aforementioned welding, structures are also known in which end portions of the top foil and the back foil (bump foil) are bent over by a bending process, with this bent portion being made to engage with an engagement groove that is formed in the inner circumferential surface of the bearing housing (for example, refer to Patent Documents 1 to 3).